Tracers have been used in the oil and gas industry to provide valuable reservoir information such as inter-well connections, heterogenetities, and water movements. Tracers can also be used in reservoir monitoring. Reservoir monitoring refers to the gathering and analysis of information from reservoirs during production. Such monitoring is used to assess the productivity of producing formations or zones within the formations from which fluids are being produced. Monitoring of produced fluids is important in order to increase efficiency of a hydraulic fracturing operation. Reservoir monitoring is further used to determine water saturation levels in the well.
Tracers may include radioactive elements and stable isotopes, chemicals, such as fluorescent dyes, and inorganic ions. However, certain radioactive elements are not environmentally friendly. Inorganic ions may require long detection times. Dyes are susceptible to decomposition under harsh conditions. Accordingly the industry is always receptive to alternative tracers and improved methods for reservoir monitoring and evaluation.